This application is related to commonly assigned co-pending application Ser. No. 09/413,609, to Christina P. Lau, entitled xe2x80x9cMethod and Mechanism for a Task Oriented Data Modelxe2x80x9d, filed the same day as the present application.
The present invention relates to object oriented programming systems, and more particularly to a task oriented structure for a data model.
Traditionally in the computer programming arts, program code and data have been kept separate. For example, in the well-known C programming language, units of program code are called functions, and units of data are called structures. In C the functions and structures are not formally connected, that is, a function can operate on more than one type of data structure, and more than one function can operate on the same structure.
Object-oriented programming, in contrast, deals with objects, in which program code and data are merged into a single indivisible entity or xe2x80x9cobjectxe2x80x9d. An object is an instance of an implementation and an interface, which models a real-world entity. The object is implemented as a computational entity that encapsulates state and operations and responds to requests. The data and methods are implemented internally in the object. A business object for example is an object containing business methods (i.e. logic) and state that is intended for use within business applications.
Objects are built using an application program commonly referred to as an object builder tool. The object builder is a program which is used to define the business objects and generate the necessary definition and implementation files in IDL (Interface Definition Language), C++ and/or Java, as will be understood by those skilled in the programming arts.
Object builders utilize a data model which provides a template of the data structure for the objects. Object-oriented data models can be adapted to a wide range of different models by changing the definitions of meta-data, such as the objects and the task trees. Meta-data as will be understood by those skilled in the art comprises the self-descriptive information that can describe both services and information. With meta-data new services can be added to a system and discovered at run-time.
The object builder in the Component Broker(trademark) toolkit from IBM utilizes a proprietary data model known as the Common Data Model (CDM), which is implemented as a binary file. In the object builder tool for Component Broker(trademark), objects are processed by performing sets of user-defined operations in the form of task trees.
The binary file format of the Common Data Model yields some advantages such as rapid saving and loading of the data model. However, these advantages are offset by a number of disadvantages. First, the binary format of the Common Data Model or CDM is not human readable and as such the data model can only be examined by using the user interface in the object builder or by viewing the code generated from the binary file. Second, the data model must be imported or exported in its entirety, i.e. component parts of the data model cannot be imported or exported. This makes it much more time-consuming to perform impact analysis and to compare different model-generated outcomes. I-or example, to compare the modeling results obtained by modifying one object, it is usually necessary to import or export the entire data model, even though the data model is substantially unchanged in any respect other than the slightly altered object.
This problem has been addressed in other data models by using a proprietary language, for example, the known Rational Rose tool utilizes a Rose mdl format file to represent the meta-data for the data model. Because the mdl format has been well publicized, objects using the mdl format can be designed and analyzed by any modeling tool which supports mdl. Using a proprietary language such Rose mdl, the meta-data is organized so that the component parts of the data model, such as objects and task trees, can be imported and exported at various different levels of generality. However, using a proprietary language limits the interoperability between the data model and other tools as these other tools will need to use parsers that are compatible with the proprietary language in order to retrieve meta-data from the data model.
Accordingly, there remains a need for generating a data model which is not confined to a proprietary language.
The present invention provides a mechanism for a task oriented data model for a development tool in an object oriented programming system.
According one aspect of the invention, the meta-data of the data model is represented using an open standard. Advantageously, by representing the meta-data using an open standard, conventional parsers for the open standard may be used to retrieve the meta-data. According to this aspect of the present invention, the data model takes the form of a document file expressed in Extensible Markup Language or XML. XML comprises a simplified subset of the Standardized Generalized Markup Language or SGML. Like SGML, but unlike other subsets of SGML such as Hypertext Markup Language (HTML), XML permits (i) users to add new defined tags to the tag set at will; and (ii) XML documents to be properly nested within one another to an arbitrary extent. In accordance with this aspect of the invention, the import and export utility in the object builder is implemented to express the data model as an XML document wherein the data elements are arranged according to a meta data model. According to this aspect of the invention, the meta data model comprises a Document Type Definition or DTD in XML.
According to another aspect of the invention, the data model incorporates a task oriented structure which mirrors the user interface in the object builder. The task tree for the user interface is represented using containment relationships defined by XML constructs specified in the Document Type Definition, i.e. the meta data model. For example, the properties and values in the SmartGuides(trademark) under the Component Broker(trademark) toolkit are represented according to this aspect of the invention as a tag with an identical label and value format. Advantageously, this task oriented data structure allows users to quickly locate and recognize the data element of interest in the data model. In addition, the task oriented structure of the data model provides the capability to export and import data elements with varying degrees of granularity.
According to an aspect of the invention, there is provided a task oriented data structure embodied in a program storage device for an object oriented application program, the object oriented application program having a user interface comprising a plurality of items, said items defining a sequence of tasks for creating one or more objects, said data structure comprising: (a) a data model expressed in the form of a document according to a meta data language; (b) said data model including a plurality of data elements; (c) each of said data elements corresponding to one of the tasks in said sequence of tasks; and (d) said data elements being arranged according to a meta data model, wherein said meta data model mirrors the sequence of tasks defined in the user interface. Said meta data model may means for validating each of said data elements and the arrangement of said data elements. Further, said meta data language may comprise XML or Extensible Markup Language, and said data elements being arranged according to containment constructs specified in said meta data model. Said means for validating may also comprise a Document Type Definition specified in XML. And, said containment constructs may comprise tag definitions according to XML.
There is also provided, in an application program for creating objects, the application program having a user interface comprising a plurality of items, said items defining a sequence of tasks for creating the objects, and said application program including an export utility for exporting document files, a export utility comprising: (a) means for exporting a document file expressed in a meta data programming language; and (b) wherein said document file comprises a plurality of data elements, each of said data elements corresponding to one of the tasks in said sequence of tasks, and said data elements being arranged according to a meta data model, wherein said meta data model mirrors the sequence of tasks defined in the user interface. Said meta data model may also include means for validating each of the data elements included in said document file. Said document file may also be expressed in XML or Extensible Markup Language, and said data elements being arranged according to containment constructs specified in said meta data file. And, said means for validating may comprise a Document Type Definition specified in XML.
According to another aspect of the invention, there is provided a computer program product for an object oriented application program for creating objects, the application program having a user interface comprising a plurality of items, said items defining a sequence of tasks for creating the objects, and said application program including an export utility for exporting document files, said computer program product comprising a program storage device; means recorded on said program storage device for instructing a computer to perform the steps of, (a) outputting a document file, said document file being expressed according to a meta data programming language; and (b) said document file comprising a plurality of data elements, each of said data elements corresponding to one of the tasks in said sequence of tasks, and said data elements being arranged according to a meta data model, wherein said meta data model mirrors the sequence of tasks defined in the user interface. Said meta data model may include means for validating each of the data elements in said document file. Said meta data language may comprise XML or Extensible Markup Language, and said data elements being arranged according to containment constructs specified in said meta data model. And, said means for validating may comprise a Document Type Definition specified in XML.
There is also provided a computer system for creating objects in an object oriented application program, the application program having a user interface comprising a plurality of items, said items defining a sequence of tasks for creating the objects, and said application program including an export utility for exporting document files, said computer system comprising: (a) means for outputting a document file, said document file being expressed according to a meta data programming language; and (b) said document file comprising a plurality of data elements, each of said data elements corresponding to one of the tasks in said sequence of tasks, and said data elements being arranged according to a meta data model, wherein said meta data model mirrors the sequence of tasks defined in the user interface. Said meta data model may include means for validating each of the data elements in said document file. Said meta data language may also comprise XML or Extensible Markup Language, and said data elements being arranged according to containment constructs specified in said meta data model. And, said means for validating may comprise a Document Type Definition specified in XML.